To connect multiple electrode layers of a three-dimensional memory device to a control circuit, a stairstep-shaped contact structure of the multiple electrode layers has been proposed. Also, a method for the three-dimensional memory device has been proposed in which a stacked body including multiple sacrificial layers is formed; and subsequently, gaps are formed by removing the sacrificial layers. The stacked body including the gaps is supported by columnar portions formed in the stacked body prior to removing the sacrificial layers.